.\" Copyright (c) 2019, 2023 Shivank Garg <shivank@FreeBSD.org>
.\"
.\" This code was developed as a Google Summer of Code 2019 project
.\" under the guidance of Bjoern A. Zeeb.
.\"
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.Dd July 25, 2023
.Dt MAC_IPACL 4
.Os
.Sh NAME
.Nm mac_ipacl
.Nd "IP Address access control policy"
.Sh SYNOPSIS
Add the following lines in your kernel configuration file to compile the
IP address access control policy into your kernel:
.Bd -ragged -offset indent
.Cd "options MAC"
.Cd "options MAC_IPACL"
.Ed
.Pp
To load the mac_ipacl policy module at boot time, add the
following line in your kernel configuration file:
.Bd -ragged -offset indent
.Cd "options MAC"
.Ed
.Pp
and in
.Xr loader.conf 5 add:
.Pp
.Dl "mac_ipacl_load=""YES"""
.Sh DESCRIPTION
The
.Nm
policy allows the root of the host to use the
.Xr sysctl 8
interface to limit the
.Xr VNET 9
jail's ability to set IPv4 and IPv6 addresses.
So, the host can
define rules for jails and their interfaces about IP addresses
with
.Xr sysctl 8
MIBs.
.Pp
Its default behavior is to deny all IP addresses for the jail if
.Nm
policy is enforced and allow/deny IP (or subnets) according to the
.Va security.mac.ipacl.rules
string specified with
.Xr sysctl 8
.Ss Runtime Configuration
The following
.Xr sysctl 8
MIBs are used to control enforcement and behavior of this MAC Policy.
.Bl -tag -width indent
.It Va security.mac.ipacl.ipv4
Enforce
.Nm
for IPv4 addresses.
(Default: 1).
.It Va security.mac.ipacl.ipv6
Enforce
.Nm
for IPv6 addresses.
(Default: 1).
.It Va security.mac.ipacl.rules
The IP address access control list is specified in the following format:
.Pp
.Sm off
.D1 jid , allow , interface , addr_family , IP_addr / prefix Op @ jid , ...
.Sm on
.Bl -tag -width "interface"
.It jid
Describe the jail id of the jail for which the rule is written.
.It allow
1 for allow and 0 for deny.
Decides action performed for the rule.
.It interface
Name of the interface the rule is enforced for.
If the interface is left empty then it is a wildcard to enforce the
rule for all interfaces.
.It addr_family
Address family of the IP_addr.
The input to be given as AF_INET or AF_INET6
string only.
.It IP_addr
IP address (or subnet) to be allowed/denied.
Action depends on the prefix length.
.It prefix
Prefix length of the subnet to be enforced by the policy.
-1 implies the policy is enforced for the individual IP address.
For a non-negative value, a range of IP addresses (present in subnet)
which is calculated as subnet = IP_addr & mask.
.El
.El
.Sh EXAMPLES
Behavior of the
.Nm
policy module for different inputs of sysctl variable:
.Bl -tag -width "1."
.It 1.
Assign ipv4=1, ipv6=0 and rules="1,1,,AF_INET,169.254.123.123/-1"
.Pp
It allow only 169.254.123.123 IPv4 address for all interfaces (wildcard) of jail 1.
It allows all IPv6 addresses since the policy is not enforced for IPv6.
.It 2.
Assign ipv4=1, ipv6=1 and rules="1,1,epair0b,AF_INET6,fe80::/32@1,0,epair0b,AF_INET6,fe80::abcd/-1"
.Pp
It denies all IPv4 addresses as the policy is enforced but no rules are specified
about it.
It allows all IPv6 addresses in subnet fe80::/32 except
fe80::abcd for interface epair0b only.
.It 3.
Assign ipv4=1, ipv6=1, rules="2,1,,AF_INET6,fc00::/7@2,0,,AF_INET6,fc00::1111:2200/120@2,1,,AF_INET6,fc00::1111:2299/-1@1,1,,AF_INET,198.51.100.0/24"
.Pp
It allows IPv4 in subnet 198.51.100.0/24 for jail 2 and
all interfaces.
It allows IPv6 addresses in subnet fc00::/7 but
denies subnet fc00::1111:2200/120, and allows individual IP
fc00::1111:2299 from the denied subnet for all interfaces in jail 2.
.El
Please refer to mac/ipacl tests-framework for wide variety of examples on using
the ipacl module.
.Sh LIMITATIONS/PRECAUTIONS
In the case where multiple rules are applicable to an IP address or
a set of IP addresses, the rule that is defined later in the list
determines the outcome, disregarding any previous rule for that IP
address.
.Sh FUTURE WORKS
Rules are given with sysctl interface which gets very complex to give them
all in command line.
It has to be simplified with a better way to input those rules.
.Sh SEE ALSO
.Xr mac 4 ,
.Xr mac 9
.Sh AUTHORS
The
.Nm
policy module was developed as a Google Summer of Code Project in 2019
by
.An -nosplit
.An "Shivank Garg" Aq Mt shivank@FreeBSD.org
under the guidance of
.An "Bjoern A. Zeeb" Aq Mt bz@FreeBSD.org .
